Thermal assembly press



April 5, 1955 G. w. SODERMAN ET AL THERMAL ASSEMBLY PRESS 3 Sheets-Sheet 1 Filed May 31 1951 S aw mv & m Q Q RT n \QN l R. 3. Q om j A w C INVENI'OQS a. m SODERMAN CJSTCLP A T TORNEI April 1955 G. w. SODERMAN ET AL 2,705,341

THERMAL ASSEMBLY PRESS Filed May 31. 1951 3 Sheets-Sheet 2 FIG. 2

Mil EN TORS a. :4! 500mm c. 4 5mm- ATTOR/Vfy April 5, 1955 G. w. SODERMAN ETAL THERMAL ASSEMBLY PRESS 3 Sheets-Sheet 5 Filed May 31, 1951 mwuvrons G. W SODERMAN c J STOLP WW A 7' TOR/VEV United States Patent THERMAL ASSEMBLY PRESS George W. Soderman, West Englewood, and Cornelius J. Stolp, Newark, N. 1., assignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application May 31, 1951, Serial No. 229,162

4 Claims. (Cl. 18-17) This invention relates to pressure molding apparatus and more particularly to apparatus of this type for molding a plastic assembly through the application of heat.

A new type of electrical assembly, as described in a joint application by H. R. Gross and H. R. Massingham, Serial No. 91,744, filed May 6, 1949, now Patent No. 2,596,237, is being used extensively in certain types of electrical communication equipment. This assembly involves heat sealing the leads of two layers of circuit components into the top and bottom edges of a pair of parallel plastic strips to form a structure in which the strips and the components mutually support each other.

In manufacturing assemblies of this type, it is necessary to provide means for heating the plastic strip edges and for applying pressure to the strips relative to the component leads in order to force the leads into the body of the strips and thereby provide the required heat-sealing action. Apparatus designed for this purpose should be desirably adapted for mass production of the assemblies, in view of the large scale use of this type of structure.

It is therefore an object of this invention to provide apparatus capable of assembling a structure of this type by pressure heat-sealing in a simple and rapid manner.

Applicants accomplish this object according to the invention by first positioning in a. fixture circuit elements and two plastic strips which are to be formed into an assembly, with the fixture then being placed in a ram type press. Heat is applied to the plastic strip edges through the element leads, and the downward movement of the ram forces these softened edges down around the leads. The ram pressure is applied through the torsional force of a main spring, with this spring being aided by a booster spring during the latter part of the ram travel.

Other objects and advantages will be apparent from the following detailed description taken in conjunction with the attached drawing, in which:

Fig. 1 is a side elevational view of the molding press;

Fig. 2 is a front elevational view of the press, showing the spring pressure means;

Fig. 3 is a view of the fixture used with the press;

Fig. 4 shows the pressure plate which fits over the fixture;

Fig. 5 shows a completed electrical assembly manufactured by the apparatus.

Before the machine is operated, the circuit components 1 and the plastic strips 2 into which they are to be heatsealed are placed in their proper positional relationship by means of the fixture shown in Figs. 3 and 4. This fixture includes a base member 3 having transversely aligned slots 4 in which are placed leads 5 of the components. Two plastic strips 2 are then laid on the tops of the leads, these strips being held in a vertical posi tion and prevented from longitudinal movement as shown by means of two slidable positioning heads 6 and 7. A top plate 8, shown in Fig. 4, which is caused to fit snugly over the base member by end projections 9, has two longitudinal slots 10 which fit over the top edges of the plastic strips and provide a means through which downward pressure may be applied to the strips.

After the plastic strips and the circuit components have been properly positioned in the fixture, the latter is moved into place in the molding machine, with the base 3 of the fixture resting as shown on shoulders 11 located between two heating elements 12. The machine is so dimensioned that with the base on these shoulders, the leads 5 will be at the level of the top of the heating elements 12 and will rest on these elements.

The molding machine itself may be of any suitable type, such as for example a hydraulic or pneumatic type of press. This machine 13 has a vertically moving ram 14, which in its downward movement bears against and forces down a carriage generally designated as 15, the carriage assembly being pivoted about the point 50, straddling the upper portion of the press and normally urged upwardly into its open position by suitable means such as a pair of springs 34, only one of which is shown, connected to brackets on each side of the press.

Two parallel shafts 16 and 17 are rotatably supported by the carriage, the shaft 16 having its ends journaled in fixed position bearings 23 on the carriage while the shaft 17 has its ends journaled in movable bearings 17. Parallel arms 18 have their outer ends fixed to the ends of the shaft 16 and are provided with notches 21 in their inner ends. Parallel arms 19 have their outer ends fixed to the ends of the shaft 17 and their inner ends provided with aligned apertures to receive reduced ends 20' of an elongate roller-like bearing members 20. The reduced ends 20 of the bearing member 20 are disposed in the notches 21 of the arms 18 thus combining the functions of the arms 18 and 19 in controlling the member 20. The fixture, on being placed within the molding machine, is approximately centered below the bearing member 20.

A spring 22 is positioned about one portion of shaft 16, its right end being fastened to the adjacent bearing 23 on the carriage 15, and the left end of the spring being fastened to a collar 24 which is rigidly mounted on the shaft 16 and rotates therewith. A second spring 26 is positioned about another portion of the shaft, the ends of spring 26 being connected to collars 27 and 28. Collar 27 is rigidly connected to the shaft 16 and rotates therewith, while collar 28, which is freely rotatable on the shaft and has projections 36 and 37, the latter carrying an adjustable screw 38, is caused by an initial torsion placed on the spring 26 to cause the projection 36 to rest against a stop 29, which is connected to the shaft 16 through an additional collar 30.

Before the press is operated the bearing member 20 is normally positioned below the plane of the axes of the shafts 16 and 17 approximately the distance it is shown above the plane in its operated position in Fig. 1. This normal position is controlled by a stop in the form of a collar 39 fixedly mounted on a shaft 16 and having a screw 39' mounted in a projection of the collar to engage a portion of the carriage 15. Also, before the press is operated, the loaded fixture is placed in the lower part of the press with the wire leads resting on the heating elements 12. When the ram and carriage are moved downwardly, the bearing member 20 comes into contact with the top plate 8 of the fixture, where its downward motion is temporarily stopped due to the fact that the plastic strips have not as yet been heated sufficiently by the wires. When this happens, the resistance of the top plate to the further downward movement of the bearing member 20 during continued downward movement of the ram 14 and carriage 15 causes the arms 18 and 19 to rotate their shafts 16 and 17 with respect to the carriage 15 in counterclockwise and clockwise directions respectively (Fig. 1). This rotation of the shaft 16 places the spring 22 under increasing torsion resulting in the application of an increasing force through the shaft 16, arms 18 and hearing member to the top plate 8 and plastic strips 2. As the carriage continues its downward movement with the ram, it strikes the adjustable screw 38 mounted on the freely rotatable collar 28, which causes this collar to stop its rotation with the shaft 16, allow the projection 36 to move away from the stop 29 and bring into use the now increasing force of the spring 26. The spring 26 therefore, supplies a booster force, to exert additional downward force on the bearing member through the shaft 16 and the arms 18 to aid in the heatsealing operation.

When the fixture is first placed in position within the press, the leads 5 of the circuit components, which rest on the top edges of the heating elements 12, receive heat from these elements and transfer it to the bottom edges of the plastic strips 2, which lie on top of the ieads im mediately above the heating elements. This application of heat to the bottom edges of the strips softens them so that when the top plate 8 of the fixture is forced down ward by the bearing member 20, it forces these edges down through the leads, which are held from vertical movement by the top edges of the heating elements, and into longitudinal U-shaped slots 32 located in the heating elements. The top plate 8 continues to be forced down until it makes contact with the body of the fixture, with the total distance traveled by the top plate representing the depth to which the leads have been heatsealed into the edges of the plastic strips. After the ram and carriage have moved downward a predetermined distance, the actuating fluid of the press is shut off, and the ram and carriage return to their normal upward position, the carriage being urged upwardly by the springs 34. The fixture may now be removed from the tool, and the plastic strips with their newly sealed-in components inverted in the fixture for the purpose of sealing a new layer of circuit components into the opposite edges, so as to form a complete rigid assembly, as shown in Fig. 5.

Shearing blades 35 are located on the carriage 15 to cut off the excess ends of the newly sealed leads during the latter part of the downward travel of the carriage.

The heating apparatus may be of any conventional type capable of maintaining the elements 12 at a constant temperature of approximately 450 F., this temperature having been found suitable for proper heating of the strips where a material, such as methyl methacrylate, is used.

In order to accommodate different sizes of loading fixtures, the position of the right hand heating element and shearing blade is made adjustable through thread connections on rods 40 and 41, respectively. The upper and lower pairs of rods are given simultaneous movement by a handle 42 acting through a connecting chain drive (not shown), this drive passing vertically through the pivotal axis 50. The upper pair of rods 41 has two sets of threading on each rod, with one set 43 being used for the shearing blade and a second finer threading 44 for moving the bearing member 20. This member moves only half as far as the blade for a given turn of the handle 42 to enable it to remain centered with respect to the top plate of the fixture. The lower rod 40 has threading 45 for moving the right hand heating element 10, this threading corresponding to the threading 43.

The combination of a main and a booster spring to provide a downward pressure against the plastic strips has the advantage of applying maximum force at a time when the lower parts of the plastic strips have become sufficiently softened by heat from the leads to allow them to be forced down through the leads and into the U- shaped slots 32.

The invention as described provides a fast and economical method of joining plastic strips and circuit components together to form a rigid compact assembly. The apparatus and method are well adapted for mass production, an important feature where these assemblies are needed in large quantities.

It is to be understood that the above described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. In a press for thermally joining an assembly of plastic strips and electrical circuit components having leads, the combination with a main press body including a press bed, a movable ram, and a source of fluid pressure for moving the ram toward the bed, of a fixture positioned in the bed for holding the components and strips in spaced relation, with the strips being vertical with respect to the bed and having their lower edges resting on top of the component leads, a top plate for the fixture which bears against the top edges of the strips, a pair of elements to support and heat the component leads and having slots shaped to receive the lower strip edges when the strips are moved downwardly during softening of the portions thereof engaging the leads, a bearing ele- 4 ment associated with the ram for applying downward pressure to thetop plate'duringthe application of heat to the strips, and shearing means associated with the ram for cutting off excess portions of the leads during the descent of the ram.

2. In a press for thermally joining an assembly of plastic strips and electrical circuit components having leads, the combination with a main press body including a press bed, a movable ram, and a source of fluid pressure for moving the ram toward the bed, of a fixture positioned in the bed for holding the components and strips in spaced relation, with the strips being vertical with respect to the bed and having their lower edges resting on top of the component leads, a top plate for the fixture which bears against the top edges of the strips, a pair of elements to support and heat the component leads and having slots shaped to receive the lower strip edges, and means for applying a downward pressure to the top plate during the application of heat to the leads,'said means comprising a carriage actuated by the ram, a shaft rotatably supported by the carriage, a main spring positioned about the shaft and having one end connected to the carriage and the other end to the shaft, a pair of arms having like ends rigidly mounted at spaced positions on the shaft, a bearing member mounted between the other ends of the arms and positioned to be vertically aligned with the top plate of the fixture, to cause the plate to interrupt the downward movement of the member and thereby place the main spring in torsion, a booster spring also positioned about the shaft and normally rotating therewith, and means for moving one end of the booster spring relative to the shaft to place it in torsion when the carriage has reached a predetermined point in its travel.

3. In a press for thermally joining an assembly of plastic strips and electrical circuit components having leads, the combination with a main press body including a press bed, a movable ram, and a source of fluid pressure for moving the ram toward the bed, of a fixture positioned in the bed for holding the components and strips in spaced relation, with the strips being vertical with respect to the bed and having their lower edges resting on top of the component leads, a top plate for the fixture which bears against the top edges of the strips, a pair of elements to support and heat the component leads and having slots shaped to receive the lower strip edges when the strips are moved downwardly during softening of the portions thereof engaging the leads, means for applying a downward pressure to the top plate during the application of heat to the strips, said means comprising a carriage actuated by the ram, a shaft rotatably supported by the carriage, a main spring positioned about the shaft and having one end connected to the carriage and the other end to the shaft, a pair of arms having like ends rigidly mounted at spaced positions on the shaft, a bearing member mounted between the other ends of the arms and positioned to be vertically aligned with the top plate of the fixture, to cause the plate to interrupt the downward movement of the member and thereby place the main spring in torsion, a booster spring also positioned about the shaft and normally rotating therewith, and means for moving one end of the booster spring relative to the shaft and thereby place it in torsion when the carriage has reached a predetermined point in its travel.

4. In a press for thermally joining electrical units having metallic leads to a plastic strip, a heating element to support the leads against movement and heat them sufiiciently to soften portions of the plastic strip, a fixture provided with means to hold the leads in predetermined spaced relationship with respect to each other and with means to locate the strip in engagement with and across the leads, and means to engage and move the strip a given distance relative to the leads while the leads soften the adjacent portions thereof whereby the leads will extend through spaced portions of the strip.

References Cited in the file of this patent UNITED STATES PATENTS 1,541,357 Johnson June 9, 1925 1,815,721 McGraw July 21, 1931 1,831,144 Shearer Nov. 10, 1931 1,973,117 Sklar Sept. 11, 1934 2,436,597 Otis Feb. 24, 1948 2,572,646 Menzel et a1. Oct. 23, 1951 

